Process for dyeing textile materials comprising a cellulose carboxylic ester with vat dyes



July 29, 1947. H. s. scum. 2,424,857

PROCESS FORDYEING TEXTILE MATERIALS COMPRISING A CELLULOSE CARBOXYLIC ESTER WITH VAT DYES Filed 001;. 21, 1945 L s L R 1 wm w m w F. S 0 .w v w (\)I.Em m2iu m .A wENBcS wzfimvm a nu T m w M mzimq mm H Mg oz wziwqk Al 1 B uzixw E NM 0 Al 9 .7 mm

OH 10 MN mN v 1 NN KN 0 0 2x8 293m 55m Patented July 29, 1947 UNITED STATES PTENT OFFICE PROCESS FOR DYEING TEXTILE MATE- RIALS COMPRISING A CELLULGSE CAR- BOXYLIC ESTER WITH VAT DYES Herbert G. Scull, New York, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey 21. Claims.

This invention relate-s to a process for dyeing textile materials, such as filaments, threads, yarns or fabrics (knitted or woven) comprising a cellulose carboxylic ester and particularly to a process for dyeing such textile materials with vat dyes.

The dyeing of textile materials, such as cotton and regenerated cellulose rayon, with vat dyes is very well known. The vat dyes can be applied to the textile materials by immersing the materials in a vat containing an alkaline solution-of the vat dye in its reduced form, followed by oxidation of the dye on the textile; this is practical in a continuous or stepwise process. Textile materials, such as cotton and regenerated cellulose rayon, can also be dyed with vat dyes by padding the materials with a vat dye in its unreduced form and then subjecting the padded material to the action of an alkaline reducing agent, followed by oxidation. These methods of applying vat dyes to textile materials comprising a cellulose carboxylic ester, howeven'have not been satisfactory, owing to the fact that the alkaline baths (vats) cause excessive saponification of the cellulose ester material, thereby detrimentally altering its characteristics.

Because some vat dyes are exceedingly stable to light, a number of efforts to devise methods for dyeing textile materials comprising a cellulose carboxyli ester with v at dyes have been made. Some of these have been almost entirely unsuccessful. In other cases, it has been proved possible to apply certain vat dyes to textile materials comprising a cellulose carboxylic ester, but the vat dyes which have been successfully applied are of the simpler types and not stable to light. With the more complex vat dyes such as the anthraquinone vat dyes, many of which are very stable to light and require alkaline reducing agents to efiect their reduction, efforts to dye textile materials comprising a cellulose oarboxylic ester have not met with success.

Among the earliest proposals for the dyeing of textile materials comprising a cellulose carboxylic ester was that of merely treating the textile material with an aqueous suspension of the vet dye having in its chemical constitution an active group (hydroxyl, amino, nitro, nitroso, etc.) content preponderant numerically over any sulfo group content. This proposal, while possibly suitable for certain low molecular weight dyes, is of no use, whatsoever, in the case of the complex anthraquinone vat dyes. Moreover, such a method would leave cotton and viscose rayon white in fabrics involving a mixture of cellulose carboxylic ester rayon and cotton or viscose rayon. Another early proposal was to treat the textile materials with vat dyes in a vat of such low alkalinity that the cellulose ester was not saponified, the vat containing a protective colloid such as gelatin or starch and a water-soluble salt, such as calcium chloride or sodium chloride. Likewise, this proposal, While possibly suitable for vat 'dyes of a simple character, is of no utilit whatsoever for the high molecular weight complex anthraquinone vat dyes. Still another proposal was to treat the cellulose ester textile material with a vat dye in a vat in which the strong alkali usually employed was replaced with an alkali phenate. This proposal was made largely in connection with efforts to dye mixed textile materials containing both cellulose ester yarn and regenerated cellulose yarn or cotton yarn. However, in operating aocordingto this proposal, itis found that the vat dyes do not color the cellulose ester yarn to deep, full shades so that it is necessary to supplement the vat dyeing with a direct dye for the cellulose ester yarn in order to bring the cellulose ester yarn to the same depth of color as the regenerated cellulose rayon yarn or cotton yarn. Moreover, operating according to this method with lightfast anthraquinone dyes, the dyes obtained on the cotton o the regenerated cellulose rayon are poor money value dyeings. Still another proposal has been to color cellulose ester textile materials with ester salts of vat dyes. However, unless special methods of. handling are employed, cellulose carboxylic ester rayon cannot be dyed with these dyes and, in any event, only a limited range of colors which are fast to light on cellulose carboxylic ester rayon are available.

I have now found a process for dyeing textile materials comprising a cellulose .carboxylic ester with vat dyes, including the light-stable, high molecular weight complex anthraquinone vat dyes. My new process is especially useful in the dyeing of piece goods containing both cellulose carboxylic ester rayon yarn and cotton yarn or regenerated cellulose rayon yarn.

It is, accordingly, an object of my invention to provide a process for dyeing textile materials comprising a cellulose carboxylic ester with vat dyes. Other objects will become apparent hereinafter.

In accordance with my invention, textile materials comprising a cellulose carboxylic ester, in which the acid radical contains from 2 to 4 carbon atoms, are padded with a liquid padding mixture comprising a vat dye, such as an anthraquinone vat dye, substantially in its unreduced form, a stable alkaline reducing agent (i. e., a.

reducing agent which is substantially inactive below 140 F. in alkaline medium) for the vat dye, an alkaline agent and a thickening agent. The dye-padded textile material is then advantageously dried without contact of its useful surface with any object during the initial part of the drying operation in which sufficient volatile liquid is removed from the padded textile material so that smearing will not occur upon contact of the textile material with any object. Promptly following drying, the textile material is aged, i. e., treated with steam until the vat dye s substantially reduced and the cellulose carboxylic ester fibers are saponified to a greater or lesser degree on their surfaces. The saponification obtained in this manner is not to be confused with the saponification which occurs in an alkaline vat. The saponification which obtains in practicing my invention is a surface saponification Which, I have found, is essential in order to obtain dyeings with anthraquinone vat dyes. Following aging, the textile material is treated with an oxidizing agent for the reduced vat dye in order to convert the dye to the unreduced or oxidized form. Following development of the color by oxidatiomthe textile material is washed with water and dried.

My invention is not to be confused with the prior-printing processes wherein vat dye pastes are printed upon textile materials in various designs, the materials dried, aged and developed. In these prior-printing processes, the textile material is printed on one side only at one time, and piece goods travel but a relatively short distance from the printing roller before the goods are supported by some means such as rollers during the drying process. While such a method of drying can be employed in printing processes, such methods cannot be employed in my new process where the textile material is padded throughout its thickness with the padding mixture, since the solid support, such as the roller. would cause smearin on the dyed surface of the material. With cotton or regenerated cellulose rayon textile materials, no problem of support during drying arises, since even the unreduced dyes are much more readily taken up by these textile materials than is the case with cellulose ester materials, and the cotton fibers or regenerated cellulose fibers, therefore, may be supported on rolls or the like with the entire surface (or width) of the fabric resting upon the support while the fabric is still Wet with'the padding solution. On the other hand, any attempt to support by means of smooth rollers a textile material comprising cellulose carboxylic ester fibers, while still wet with the padding mixture, would result in smearing of the dye which is only on the surface of each carboxylic ester fiber at that point in the process. Moreover, in printing processes the textile material is pulled under considerable tension in order to obtain proper registration of the pattern. Contrasted with printing processes, the textile material in my new process is under substantially no tension, i. e. it is not pulled excessively during or after padding: only sufilcient tension is applied to the goods to carry it through the various operations.

This distinction is further emphasized by the fact that printing processes always employ a paste, 1. e. a mixture of the various components necessary for printing which mixture has a texture with suificient body that it is held uniformly in the engravings of the printing rolls until deposited upon the textile material which depositing occurs uniformly and with a permanent sharp contour for the design being printed; in block screen printing, pastes must be of a sufficient thickness to prevent flooding or flowing in the design when the squeegee is moved across the screen. Distinguished from such pastes my process employs 2. padding mixture in the form of a liquid which readily flows upon the textile material, permeates the fabric and coats the individual fibers of the material. Printing pastes are wholly unsuited for use in my process because they would not spread and permeate the fabric and conversely my liquid padding mixtures are wholly unsuited for printing because they would not be held uniformly in the engraving and would spread over and permeate the fabric.

In practicing my new process, the dye-padded textile material is dried without contact of its useful surface with any object during the initial part of the drying operation. The useful surface of a fabric may be defined as that which is coextensive with that portion of the fabric normally intended to be made into garments, such as that between the selvages or that between the edge portions that would normally be trimmed off and discarded. When I specify drying of the textile material without contact, I mean without contact during the drying operation] When the padded material leaves the padding rolls it may be batched by rolling the fabric in large rolls but the drying operation should normally follow before atmospheric drying of the exposed edges of the rolled fabric occurs sufiiciently to cause migration of the dye. Also the padded fabric may be conducted directly from the paddin rolls over an endless blanket, or even over smooth rolls so long as such blanket or such rolls are kept clean (in their rotation) and padding mixture i not allowed to accumulate on the surface thereof. I do not regard this portion of the transit of the fabric through my process as being part of the drying operation, as any drying at this point is merely incidental. This drying operation without contact can be accomplished by taking the end of the textile material as it comes from the padding operation and carrying it through a drying atmosphere until the material is dry enough so that it can be passed over a roller or other suitable supporting means without marring the padded surface. Still another method of conducting the drying of the dye-padded material is to support the material in a horizontal position by means of an air cushion. Such a cushion is provided by a suitable blast of air from below and from above the material, the two blasts of air serving to counter-act one another and cushion or support th dye-padded material while it is being passed through the dryin atmosphere. Normally I have found that if roughly 40 per cent of the Volatile material contained in the padding mixture picked up by the fabric in the padding operation, is removed in the drying operation without contact of the fabric with any object, the fabric may then contact rolls, conveyors or the like without marring the fabric surface.

One manner of practicing my invention is illustrated in the accompanying drawing which is a diagrammatic representation, in section, of one embodiment of my invention. In this drawing, a fabric comprising cellulose carboxylic ester rayon yarn is carried over guide rollers 10 into the box I I of a padding machine, where, supported by a series of rollers [2, it is thoroughly treated With a padding mixture comprising a light-fast..unreduced. anthraquinone vat rdye, a l reducing. agent for the" vatlfdye. an an; alkaline agent, as hereinafter rdescribed. Normally: the paddingrmixture is? maintained: at room temperature .(60' to 80:*F.)a1th0llgh-'I may maintain the mixture: at .higher temperatures; suchzas-100 F. or even 150-F. or somewhatt-more, depending upon whether :undue" saponification takes place, inawhi'ch event a'lower temperature would wbe employed. :From the box I l; the fabric is carried throughpadding rollers -13 -where--it is I squeezed, -the1 pressure on v the .-pa;ddlng --rollers being adjusted: by means of an adjustment mechanism-M to leave-.about65lper cent,=based upon the weight-of the fabric, ofpadding mixture in the fabric. -From the padding rollers I3, the fabric is taken by its end, carried. over fabric covered roller 15 (constructedwith an endless belt of blotting cloth as described in Bromle U S. Patent-No. 2,175,051, dated October-3; 1939) and then carried into a drying towerthrough an opening in the bottom of the left-hand casin -l 6. Air, .which may bepreheated, is blown into the tower on eitherside of the .fab-ric. throughinlets I IV and is-di-rected upwardsin the towerbymeans of baffleslil. .Heatingelements, such as steam coils lB,-are' positioned on either side of the casingl 16. The fabric .is carried to a height. which permits the fabric-to become. dry. enough that contact with a solid object will .not mar. or smear the padding mixture on the fabric, "Ihis height, of course, will vary depending-upon the efiiciency of the drying atmosphere in the drying tower and .the rate at which the fabric is. moved through. the drying tower. Th rate .at which the fabricmoves through the drying tower. is deter-mined by the weight'of the fabric -and"may vary from a few yardspenminute' for heavy" constructions to 125 yardsor even .moreper :minute for very light materials, for example. When-the fabric is dry enough to be brought in contact with an object,i-t.is carried overa: guide rollerfifilll and downwardswthrough .the-right-hand casing 2! which containsoutlets .for air, and thenceout of the"drying.tower. .The fabric is then carried across guide. rollers.l23.-and.24.. and into a' steam chamber wherein it returns over a guide roller 25. In' this steam chamber," the'fa'bricis "subjected to an atmosphere of moist steam above 212 admitted to the steam chamberathrough perforated steam pipes 26 which a'respositioned in water Wells 2'1. The-steam chamber contains heating elements, such as steam coils-28. positioned on its walls. The steam coils aid in preventing condensation of the steam which travels upwards in the'chamber. and. escapesthrough a valve 29 which can be adjustedto regulate the flow of steam. Condensation of the ste-amnear the top of "the chamber is also retarded byaa steam chest30 which is equipped with: a drain 1 3| 'In the steam chamber the surface of..thecellulose carbox'ylic ester rayon yarn is saponified 1 and the anthraquinone vat dye is reduced. Erorn the steam chamber, the fabric issues across guide rollers 32 and 33 into an oxidizing bath contained in a tank 34. In the oxidizing baththe fabric is thoroughly treated with a oxidizin ..mixture (as'described hereinafter) while supp0rted-on rollers 35, followed by a'skying operation, if necessary, in order to oxidize the reduced-anthraquinone vat dyes. From the oxidizingbathythe fabricissuesover av guide rollertt-andeis carried to skying, washing and drying operations.

My-invention is directed to the dyeing of texstiles containing any percentage (from 1. to i100.%)

:"6 r of cellulose carboxylic .ester rayon fibers, filaments or yarn, with any" kind of vat dye espe- -*cially. light-fast anthraquinone vat dyes. Moreover, my invention is further especially directed 5 ,to the dyeing of textiles containing-both regenerated cellulose .yarn (e. .g., viscose yarnor cuprammonium yarn), cotton yarn or Wool-yarn .and cellulose carboxylic ester yarn, with lightfast vat dyes, which dye both yarns to the same 10 cast andapproximately the same depth. Vatrdyes which are aifected by atmospheric acids. should be avoided. 'Theifollowing vat dyes have been found to be unaffected by atmospheric deterioration and fast tolight" for at least 40 hours .in

5: light shades "when applied to' cellulose. acetate yarn:

' Dyes'listed under Color Index No.- 1151, e. g.,

Indanthrene Brown RAP (paste) 2o Dyes.listed.under Color Index No. 1097, e...g.,

'Carbanthene Golden Orange RRT (paste) Dyes listed. vunder Color Index No. 1152,. e.-.g.,

.Calcosol Brown GDbl. Pst. .Dyes'. .listed under Color Index Ponsol Olive AR Dbl. Pst. 'Dyesi listed .under Color Index.

. ".CibanoneBlue, 3G.Dbl. Pst. Dyes listed .under Color. Index -.Ca1cosol Red BN Dbl. Pst. Dyeslisted underColor Index No...1l)96,

.Indanthrene Golden OrangeGA Pst. Dyes .listedunder Color Index-No. 1101,

- Ponsol. Jade Green.Dbl. 'Pst. Dyes listed under. Color Index. No.- 1104,

.Amanthrene Brilliant Violet RR 'Pst.

No. 1150, e., g.,

- hydroxides, mixtures ofalkali metal hydroxides and .alkali metal carbonates or mixtures of trialkali metal. phosphatesand alkali metalcar- --...bonates. --Any-.--alkaline vat dye reducing. agent I cansbe employed which- .will not cause substan- .tial reduction :ofthe vatdyein the padding mix- :lture at.80F-. over. aperiod of '24 hours, e.'g.,:so-

dium -formaldehyde:-.sulfoxylate or some. other alkali. .metal aldehyde sulfoxy1ate,-- or ametal: aldehyde sulfoxylate, such as normaltfzinc formalggvhydevsulfoxylate. -As .the thickening -..agent, Britishtgum; starch, vegetable mucilage; dry gum on. Supertex; gum' T+125 .(karaya' gum): can beused. 'Asr antioxidants; phenols, suchxas. .hydroquinone ore-salicylic,,acid;.:may:be used. zAlso; glucose or e'alkali metal" hydrogen sulfites'mayabe used; as

vantioxid'ants. :As; penetrating agents; or assistants, .glycerines. o1. ig1yc0ls;1a1'ei advantageously employed. .Diethylene *glycol is 18,111. especially usefulassistant. :As dispersing agents, aTergitol 70. N0;-- 4:. (sodium sulfateof higher secondary alco- H hols) sulfite "cellulose :waste. liquors, but'ylated naphthalene sulfonic acids" or dipotassium glycol I disulfate can'beaused.

The; following example z will; serve to illustrate 75, ;further -.:the;-manner' of;practicing.v my. invention;

- ing.

Example A stock mixture was prepared by making a solution of the following materials:

Ten parts by weight of an anthraquinone vat dye, such as Ponsol Olive G Paste was diluted with parts of water, which mixture was then added to 80 parts of .the .above-described'stock mixture to make 100 parts of padding mixture. The resulting padding mixture was placed in a suitable padding machine, such as the padding machine depicted diagrammatically in the accompanying drawing. Piece goods consisting of viscose rayon yarn and 30 per cent cellulose acetatevrayon yarn was run through the padding mixture and through the padding rolls, the pressure on the rolls being adjusted to leave about 65 parts of padding mixture in 100 parts of the goods; this is known in the trade as 65 per cent pick up. As the goods came from the padding operation, it was taken by its end and carried into a drying tower, such as the drying tower depicted diagrammatically in the accompanying drawing, and dried without contact during drying of its useful surface with any object until it was dry enough that contact with a roller did not cause smearing or marring of the dyed surface of the goods. The goods was then passed over a roller and carried out of the drying tower, with only sufiicient tension applied to the goods to carry it through the various operations. (The goods should not be pulled excessively during or after padding. Various of the rolls over which the goods passes may be synchronously driven. to reduce the tension upon the goods during the various stages of the process, if desired.) The drying was conducted to remove at least 75 per cent of the volatile in the goods after padding. (Better results are obtained with the removal of 85 per cent or 90 per cent or even 100 per cent of the volatile. Drying can be facilitated by the passage of warm air in the drying tower. Heat radiators or infrared radiators can be positioned at advantageous places in the drying tower to facilitate drying.)

After drying the goods, it was drawn directly through a steam chamber, such as illustrated diagrammatically in the accompanying draw- (The goods can be batched before entering the steam chamber, and, if batched, should be cooled while batched. A chimney ager can be employed as the steam chamber.) In the steam chamber, the goods was subjected to the action of moist steam while the chamber was maintained at a temperature of from 212 F. to 270 F., for from 3 to 4. minutes. During this steam treatment the cellulose carboxylic ester fibers were saponified on their surface and the vat dye was reduced and thereupon penetrated into the saponified surface of the fibers- Such surface saponification most-desirably takes place to a depth which is only a fraction (the outer fraction) of the radius of the fiber (for instance 1% to K; of the radius) and the concentration and character of the various components of the padding mixture and the temperature and time of the various steps is regulated, generally speaking, so that surface saponification of only a small fraction of the depth of the fiber takes place.

After steaming, the goods was subjected to oxidation. (The goods can be batched before subjecting to oxidation.) While there are various known ways of developing anthraquinone vat dyes by oxidation, an oxidizing bath containing 2 g. of sodium dichromate and 5 g. of 30 per cent aqueous acetic acid per liter is suitable. The goods was immersed in such an oxidizing bath at F. until the vat dye was oxidized. After oxidizing, the goods was skyed and run in rope form through cold water and washed at 180 F. on a machine styled after the Rodney Hunt system. The goods was then rinsed well and either extracted or suctioned and then dried. The goods as processed was found to have been dyed a deep, uniform, olive gray color which was highly resistant to light fading, washing, atmospheric gas fading, crocking, etc., and to have maintained the characteristic feel and hand of the original goods. The stock mixture employed in the above example can also be made up in accordance with the following formulas:

I. A solution of the following materials was prepared:

Potassium hydroxide oz 7.5 Potassium formaldehyde sulfoxylate oz 32 Salicylic acid oz 3 Water qt 2.5

To the resulting solution were added the following substances:

British gum (70% converted, 4 lbs. per gallon) qt 1 Urea oz 20 Thio-di-glycol ether oz 4 Tergitol #4 oz 0.25

II. A solution of the following materials was prepared:

Trisodium phosphate oz 12 Sodium carbonate oz 4 Sodium formaldehyde sulfoxylate oz 28 Hydroquinone oz 3 Water qt 2.5

To the resulting solution were added the following substances:

Supertex T- qt 1 Urea oz 20 Thio-di glycol ether oz 4 Tergitol #4 oz 0.25

III. A solution of the following materials was prepared:

Sodium hydroxide oz 5.5 Sodium formaldehyde sulfoxylate oz 28 Hydroquinone oz 3 Water qt 2.5

To the resulting solution were added the following substances: British gum (70% converted, 4 lbs. per gallon) d qt 1 Urea oz 20 Triethylene glycol oz 4 IV. A solution of the following. materials was prepared:

Sodium carbonate oz Sodium hydroxide oz 2.5 Sodium formaldehyde sulioxylate oz 28 Hydroquinone oz 3 Water qt 2.5

To the resulting solution were added the following substances:

Supertex T-125 qt' 0.5 British gum (70% converted, 4 lbs. per gallon) qt 0.5 Urea oz Sodium thiocyanate oz 4 Tergitol #4- oz 0.25

V. A solution .of the following materials was prepared:

Potassium carbonate oz 16 Potassium formaldehyde sulfoxylate oz 32 Hydroquinone' oz 3 Water qt 2.5

To the resulting solution were added the following substances:

Supertex gumT-l (Jacques Wolf &-Co., Passaic, N. J.) (solubilized karayagum) qt 1 Urea. oz 20 Diethylene glycol oz 4 Tergitol le oz 0.25

VI. A paste of the following materials was prepared:

Normal zinc formaldehyde sulfoxylate oz 16 Sodium formaldehyde sulfoxylate oz 8 Thiodiglycol 0z 2 Sodium carbonate cz 16 Water qt 2 /2 Tergitol #4- oz 0.25

Disperse the above paste with a suitable grinding or dispersing machine, i. e., ball mill or colloid mill; Add to the dispersed mass: 1 qt. British gum (70% converted, 4 lbs. per gallon).

In a manner similar to that illustrated in the above example, any-other textile materials comprising cellulose carboxylic esters can be vat dyed. For instancee, one may desire to employ much higher percentages (than referred to in the abOVe example) of cellulose-acetate fibers in the fabric to be dyed by my process, e. g., a fabric composed of about equal parts by weight of cellulose acetate rayon and viscose rayona fabric not uncommon inthe trade, or a fabric constructed of 60 per cent spun cellulose acetate rayon and 40 per cent cellulose acetate filament yarn. Textile materials comprising 100 per cent cellulose carboxylic esters should not be excessively pulled under any circumstances. Again some fabric constructions may employ 50 per cent acetate and approximately*25 per cent viscose and 25 per cent cotton; such fabrics can readily be dyed by my process. Again some fabrics may be predominately viscose or predominately cotton and have reason to contain only a few per cent (such as 20 per cent or 10 per cent) of cellulose carboxylic ester fibers such as cellulose acetate; such fabrics can readily be dyed by my process. In fact, as above stated, my process has application to any fabric containing any percentage from 1 to 100 per cent, by weight, of cellulose carboxylic ester fibers, filaments or yarns. As explained, theviscose or cotton content of the fabric dyes readily and furnishes no particular problem; however, the cellulose carboxylic ester fibers, as pointed out do not readily absorb vat dyes. By utilizing my process, fabrics containing cellulose carboxylic ester fibers or filaments are handled in such a manner that the padding mixture containing the dye is evenly deposited on the surface of the cellulose carboxylic ester fibers and dried before contact of the coated fibers with any object; the drying step acts to cause the padding mixture to cling with sufficient adhesivity to the fiber surfaceto permit the fabric to be handled without disturbing the coating. The reduction step (steaming) performs a two-fold function in that the surface of the cellulose carboxylicester fiber is saponified sufficiently to permit thedye to penetrate the fiber and the dye is at the same time reduced-to a form which is readily absorbed by the saponified surface. Thus by acombination of all of these steps, I have been able to obtain even and permanent dyeings of cellulose carboxylic ester fibers, which result has not, to my knowledge, been possible heretofore in the art.

Cellulose oarboxylio esters which are employed 'in the manufacture of textile materials include the partiallyhydrolyzed as Well as the unhydrolyzed cellulose acetates, cellulose propionates, cellulose butyrates and the partially hydrolyzed as .well as the unhydrolyzed mixed esters of cellulose, such as cellulose acetate-propionate and cellulose acetate-butyrate. All of these cellulose carboxylio esters consist of a cellulose portion or radical and an acid radical which contains from 2 toe carbon atoms and fabrics containing fibers, filaments or yarns of all such esters can readily be dyed by my process. However, when employing textile materials made fromyarn which is madefrom cellulose carboxylic esters containing higher percentages of acid radicals, ve. g. the above-mentioned unhydrolyzed cellulose carboxylic esters, the saponificationshould be effected to a greater extent than when employing textile materials made from-yarn which is made-from cellulose 'carboxylic esters containing lower percentages of acid, radicals, e. g., partially hydrolyzed cellulose carboxylic esters. Greater saponification can be obtained .by extending the time of steaming operation and/or by increasing the concentration of the alkaline agent.

Typical vat dyes .are described in The Synthetic Dyestuffs and Intermediate Products, by Gain andThorpe, 7th ed (1934), Lippincott Com pany, Philadelphia, page. 226 et seq.

WhatI claim as my invention and desireto be secured by Letters Patentof the United States is:

1; A process.-for.uniformly dyeing in solid, color throughout its thicknessa .fibrous textile material comprising cellulose carboxylic esterfibers, inwhich'esterthe acid radical. containsfrom 2 to-4 carbon atoms, without detrimentally altering thephysical. characteristics of the original fibers of-the; textile; material, comprising padding the textile-material throughout its thickness'with a liquid padding'mixture comprising a substantially unreduoed vat. dye, sufiicient alkaline reducing agent which. is substantially inactive-at temperatures .up. to F. to accomplish reduction of the vat: dye, and'sufii'cient alkaline agent. to convert the reduced vat dye to its salt form and to causesurface saponification' of. a small fraction of the depth of the ester fibers," drying the padded textile material at an elevated temperature, while maintaining it in aihorizontal position by means of an air cushion, withouttcontact of its useful surface with any object during the drying operation until the padding mixture on the material is dry enough that it will not smear upon contact with a solid object, steaming the dried textile material at a temperature of from about 212 F. to about 270 F. in order to reduce substantially completely the vat dye and in order to saponify the surface of the cellulose carboxylic ester fibers, and treating the steamed textile material with an oxidizing agent to oxidize the reduced vat dye. V

2. A process for uniformly dyeing in solid color throughout its thickness a fibrous textile material comprising cellulose carboxylic ester fibers, in which ester the acid radical contains from 2 to 4 carbon atoms, without detrimentally altering the physical characteristics of the original fibers of the textile material, comprising padding the textile material throughout its thickness with a liquid padding mixture comprising a substantially um'educed anthraquinone vat dye, suflicient alkali metal formaldehyde sulfoxylate reducing agent which is substantially inactive at temperatures up to 140 F. to accomplish reduction of the anthraquinone vat dye, and sufiicient alkali metal carbonate to convert the reduced anthraquinone vat dye to its salt form and to cause surface saponification of a small fraction of the depth of the ester fibers, drying the padded textile material at an elevated temperature, while maintaining it in a horizontal position by means of an air cushion, without contact of its useful surface with any object during the drying operation until the padding mixture on the material is dry enough that it will not smear upon contact with a solid object, steaming the dried textile material at a temperature of from about 212 F. to about 270 F. in order to reduce substantially completely the anthraquinone vat dye and in order to saponify the surface of the cellulose carboxylic ester fibers, and treating the steamed textile material with an oxidizing agent to oxidize the reduced anthraquinone vat dye.

3. A process for uniformly dyeing in solid color throughout its thickness a fibrous textile material comprising cellulose acetate fibers, without detrimentally altering the physical characteristics of the original fibers of the textile material, comprising padding the textile material throughout its thickness with a liquid padding mixture comprising a substantially unreduced anthraquinone vat dye, sufficient alkaline reducing agent which is substantially inactive at temperatures up to 140 F. to accomplish reduction of the anthraquinone vat dye, and sufiicient alkaline agent to convert the reduced anthraquinone vat dye to its salt form and to cause surface saponification of a small fraction of the depth of the cellulose acetate fibers, dryin the padded textile material at an elevated temperature, while maintaining it in a horizontal position by means of an air cushion, without contact of its useful surface with any object during the drying operation until the padding mixture on the textile material is dry enough that it will not smear upon contact with a solid object, steaming the dried textile material at a temperature of from about 212 F. to about 270 F. in order to reduce substantially completely the anthraquinone vat dye and in order to saponify the surface of the cellulose acetate fibers, and treating the steamed textile material with an oxidizing agent to oxidize the reduced anthraquinone vat dye.

4. A process for uniformly dyeing in solid color throughout its thickness a fibrous textile material comprising cellulose acetate fibers, without detrimentally altering the physical characteristics of the original fibers of the textile material, comprising padding the textile material throughout its thickness with a liquid padding mixture comprising a, substantially unreduced anthraquinone vat dye, sulficient alkali metal formaldehyde sulfoxylate reducing agent which is substantially inactive at temperatures up to F. to accomplish reduction of the anthraquinone vat dye, and sufficient alkali metal carbonate to convert the reduced anthraquinone vat dye to its salt form and to cause surface saponification of a small fraction of the depth of the cellulose acetate fibers, drying the padded textile material at an elevated temperature, while maintaining it in a horizontal position by means of an air cushion, without contact'of its useful surface with any object during the drying operation until the padding mixture on the textile material is dry enough that it will not smear upon contact with a solid object, steaming the dried textile material at a temperature of from about 212 F. to about 270 F. in order to reduce substantially completely the anthraquinone vat dye and in order tosaponify the surface of the cellulose acetate fibers, and treating the steamed textile material with an oxidizing agent to oxidize the reduced anthraquinone vat dye.

5. A process for uniformly dyeing in solid color throughout its thickness a fibrous textile material comprising cellulose acetate fibers, without detrimentally altering the physical characteristics of the original fibers of the textile material, comprising padding the textile material throughout its thickness with a liquid padding mixture comprising a substantially unreduced anthraquinone vat dye, sumcient sodium formaldehyde sulfoxylate reducing agent to accomplish reduction of the anthraquinone vat dye, and sufiicient sodium carbonate to convert the reduced anthraquinone vat dye to its salt form and to cause surface saponification of a small fraction of the depth of the cellulose acetate fibers, drying the padded textile material at an elevated temperature, while maintaining it in a horizontal position by means of an air cushion, without contact of its useful surface with any object during the drying operation until the padding mixture on the textile material is dry enough that it will not smear upon contact with a solid object, steaming the dried textile material at a temperature of from about 212 F. to about 270 F. in order to reduce substantially completely the anthraquinone vat dye and in order to saponif the surface of the cellulose acetate fibers, and treating the steamed textile material with an oxidizing agent to oxidize the reduced anthraquinone vat dye.

HERBERT G. SCULL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,205,032 Chambers et al June 18, 1940 2,067,927 Kern Jan, 19, 1937 2,107,526 Dreyfus Feb. 8, 1938 2,318,133 Wentz May 4, 1943 2,089,920 Aubauer Aug. 10, 1937 (Other references on following page) Number Number Name Date OTHER REFERENCES schlegel July Knecht et a1., Principles and Practice of TeX- Dreyfus May tile Printing, 3d ed., London 1936, pp. 964 and 965. Lubs July 9 9 Knecht, Princip. Prae. Textile Printing, 3d ed., Kern 25, 1941 5 London 193 3 FOREIGN PATENTS Hopkins: Journ. SOC. Dyers 86 Colourists, Dec.

1941, vol. 57, pp. 3584362.

Country Date Deady: Am. Dyestuff Rep., Nov. 15, 1937, pp. Great Britain July 11, 1932 691-4, Great Britain Oct. 17, 1929 10 Rayon Textile Monthly, Nov. 1944, pp. 82, 85, 86. 

